SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de5a4c6c5221a020897b1fae3ecf9805884e82c8016a578829fb30145f4edd38' 
  AND token = 'KRmnPHw0YnyoMGbXhnod4uJzUG7lJVKl8/6Ms+w//vM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}